At one stage, the DC Universe was actually comprised of an infinite number of alternative Earths (the multiverse), that could be travelled between without too much difficulty. Now, the DC Universe is made up of an infinite number of "hypertimelines" known collectively as Hypertime, that may flow into each other and split off to create alternative pasts and alternative futures, but that can only be travelled between only with great difficulty.

Without going into too much detail, the DC superhero comics we read are all set on one timeline with a single consistent history, but the history may be altered at any time by hypertimelines merging and diverging. This allows retcons to take place without needing to pull apart the entire DC Universe and rebuild it (as happened in Zero Hour).

Gods

There are a number of god-like beings in the DC Universe.

There are the Old Gods of the various Earth pantheons, such as the Greek gods known to the Amazons on Paradise Island and the Roman gods from whom Captain Marvel derives his powers.

Apart from Old Gods and New Gods, there appears to be a God that created all. The Spectre is God's agent of vengeance, and the angel Zauriel was briefly a member of the JLA.

Hell exists, and is inhabited by a multitude of devils and demons, including Lucifer, Etrigan and Neron.

Other planes of existence

The 5th dimension is home to beings that have immense power when visiting our dimension, but are regulated by strict (possibly self-imposed) codes of behaviour. Mr. Mxyzptlk is forced to return to the 5th dimension if he can be tricked into saying his name backwards, and Johnny Thunder's thunderbolt would do only what it was ordered to do by his owner.

The phantom zone (or stasis zone) is where Valor waited a thousand years to be cured of lead poisoning, where Brainiac built a version of Krypton and where people from Bgtzl can partially enter at will to become intangible.

Pocket universes have sometimes been created by immensely powerful beings. Supergirl came originally from a pocket universe that was destroyed by three Kryptonian villains, and some members of the Legion of Super-Heroes have spent time in a pocket universe created by the Time Trapper.

History

Our point of view

While some characters that now inhabit the DC Universe were first published in 1938, the DC Universe really began in 1940, with the debut of the Justice Society of America in All-Star Comics #3. From then on, DC characters often appeared in each other's titles and fought each other's villains, and throughout the Golden Age the DC Universe was a world much like ours, with a few extra cities.

In the Silver Age, however, things got a little bit more complicated. At first, DC's Golden Age characters either weren't mentioned, or were passed off as mere comic book characters (as with the Golden Age Flash). In 1960, however, "A Flash of Two Worlds" was published in Flash #123. Here, Barry Allen accidentally vibrated his way to an alternative reality, and found himself in Keystone City, the home of Jay Garrick, the Golden Age Flash. This set the stage for the Justice League of America to meet the Justice Society of America, and the concepts of Earth-1 (home of the Silver Age characters) and Earth-2 (home of the Golden Age characters) were introduced. More Earths were discovered, and the multiverse was born.

Eventually, the powers-that-be at DC decided that the multiverse was just too confusing for new readers, and should be wiped out. In 1986, the Crisis on Infinite Earths was published, and ultimately resulted in all the multiple Earths being crammed together into one single reality. DC also took this opportunity to reboot some of their characters and rewrite their history. Superman, it was established, gained his powers only in his late teens, had never adventured as Superboy, and had his powers toned down significantly. Supergirl never existed. Wonder Woman's story started again from the beginning, so all previous Wonder Woman stories were simply wiped out.

Of course, some parts of the DC Universe adapted better than others. Perhaps the worst affected part of the DC Universe was the far future of the Legion of Super-Heroes. The Legion started off in the pages of the Superboy comics, and had a rich history of adventures with Superboy and Supergirl. Now that both these characters simply didn't exist, the writers of the Legion were forced to come up with torturous convoluted explanations for the resulting gaps in Legion history.

These inconsistencies, and others (such as problems with Hawkman's history) prompted DC to try and fix it all again with Zero Hour in 1994. Here, the DC Universe was essentially destroyed and rebuilt, allowing any continuity problems to be fixed. The Legion of Superheroes was rebooted, and forty years of Legion history erased.

Once again, however, the continuity fixes weren't completely successful. For example, the post-Crisis Superman had met the pre-Zero Hour Legion, and commented on this fact to the post-Zero Hour Legion. It started to look as if yet another continuity fix would be needed in a few more years.

In a final attempt to deal with continual revisions of DC history, the concept of Hypertime was introduced in The Kingdom in 1998. Here it was officially established that the history of the DC Universe is malleable, and may change when required without having to be torn down and rebuilt. Hypertime also re-introduced the possibility of alternative timelines, making even the Elseworlds comics "true" in some sense.

Their point of view

Before talking about the history of the DC Universe we have to discuss briefly how time passes there. The Silver Age started for us in the mid 1950s, but in the current version of DC history Superman and Batman have been around since then, but are still in their mid 30s. Wally West was introduced as a teenaged Kid Flash in 1960, but is currently in his mid 20s. To deal with this discrepancy the time since the beginning of the Silver Age is compressed to fit whatever matches the ages of current heroes.

When DC published Zero Hour, they included an official timeline of the DC Universe that had the Silver Age heroes debuting "10 years ago", and the Crisis happening "4 years ago", so it looked like about 5 of our pre-Crisis years make 1 DC year, and about 2.5 of our post-Crisis years make 1 DC year. If we keep that sort of formula we have the Silver Age starting "13 years ago" and the Crisis "7 years ago".

Using the above as a guide, a very brief current history of the DC Universe is roughly outlined below, subject to whatever alterations may be made in the future, and subject to further compressions of "comic time".

The Justice League loses UN support, and three different branches of the League are formed, led by J'onn J'onzz (Justice League Task Force) Wonder Woman (Justice League of America) and Captain Atom (Extreme Justice)